Coated polyester preforms and method of making same

Abstract

This invention relates to articles made of polyester, preferably polyethylene terephthalate (PET), having coated directly to at least one of the surfaces thereof one or more layers of thermoplastic material with good gas-barrier characteristics, and novel methods of making such articles. Preferably the barrier-coated articles take the form of preforms coated by at least one layer of barrier material and the containers blow-molded therefrom. Such barrier-coated containers are preferably of the type to hold beverages such as soft drinks, beer or juice. The preferred barrier materials have a lower permeability to oxygen and carbon dioxide than PET as well as key physical properties similar to PET. The materials and methods provide that the barrier layers have good adherence to PET, even during and after the blow molding process to form containers from preforms. Preferred barrier coating materials include poly(hydroxyamino ethers). In one preferred method, preforms are injection molded then barrier-coated immediately thereafter.

What is claimed is:  
     
       1. A injection molded preform comprising: 
       a body portion comprising a wall portion and an end cap wherein said body portion comprises  
       a first layer comprising a thermoplastic polyester; and  
       a second layer comprising an amorphous thermoplastic material;  
       wherein said first layer is thinner in the end cap than in the wall portion and the second layer is thicker in the end cap than in the wall portion and said first layer is about ⅓ of the total thickness of the end cap and about ⅔ of the total thickness of the wall portion;  
       wherein the amorphous thermoplastic material of the second layer is selected from the group consisting of (i) phenoxy-type thermoplastic, (ii) copolyester of terephthalic acid, isophthalic acid and at least one diol, and (iii) recycled polyester. 
     
     
       2. The injection molded preform of  claim 1 , wherein at least one of said first and second layers comprises a barrier material. 
     
     
       3. The injection molded preform of  claim 1 , further comprising a third layer comprising recycled polyester. 
     
     
       4. The injection molded preform of  claim 1 , wherein said second layer consists of a plurality of microlayers comprising barrier material. 
     
     
       5. The injection molded preform of  claim 1 , wherein said first layer is the innermost layer. 
     
     
       6. The injection molded preform of  claim 1 , wherein said preform is made by an overinjection process. 
     
     
       7. The injection molded preform of  claim 1 , wherein said polyester of the first layer is polyethylene terephthalate. 
     
     
       8. An injection molded preform comprising: 
       a body comprising wall and end cap portions, wherein the body is formed from at least a first and second layer, said first layer comprising a first thermoplastic polyester and said second layer comprising an amorphous thermoplastic material; wherein  
       the first layer is thinner in the end cap than in the wall portion;  
       the second layer is thinner in the wall portion than it the end cap; and  
       said first layer is about ⅓ of the total thickness of the end cap and about ⅔ of the total thickness of tie wall portion;  
       where the amorphous thermoplastic material of the second layer is selected from the group consisting of (i) phenoxy-type thermoplastic, (ii) copolyester of terephthalic acid, isophthalic acid and at least one diol, and (iii) recycled polyester.  
     
     
       9. The injection molded preform of  claim 8  wherein the first layer is the innermost layer of the preform. 
     
     
       10. The injection molded preform of  claim 8  wherein the first and second thermoplastic materials are the same thermoplastic material. 
     
     
       11. The injection molded preform of  claim 8 , wherein at least one of said first and second layers comprises a barrier material. 
     
     
       12. The injection molded preform of  claim 8 , wherein at least one of said first and second layers comprises recycled polyester. 
     
     
       13. The injection molded preform of  claim 8 , further comprising a third layer on the second layer. 
     
     
       14. The injection molded preform of  claim 8 , wherein said first thermoplastic polyester is polyethylene terephthalate.